Milo: Actually shorten step text
Milo: Actually shorten step text

Continuation of the fix here: https://codereview.chromium.org/2993623002/

BUG=

Review-Url: https://codereview.chromium.org/2991383002

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go